Effect of Microstructure Change on the Crack Formation of Heat Treated Ti-Al Intermetallic Compound

0380662 - ÚFM 2013 RIV CZ eng C - Conference Paper (international conference)
Hasegawa, H. - Nomura, M. - Haga, H. - Dlouhý, Ivo - Fukutomi, H.
Effect of Microstructure Change on the Crack Formation of Heat Treated Ti-Al Intermetallic Compound.
New Methods of Damage and Failure Analysis of Structural Parts. Ostrava: VŠB-TU Ostrava, 2012, s. 185-192. ISBN 978-80-248-2802-2.
[New Methods of Damage and Failure Analysis of Structural Parts. Ostrava (CZ), 10.09.2012-14.09.2012]
R&D Projects: GA MŠMT(CZ) ME10117
Institutional support: RVO:68081723
Keywords : microstructure control * beta phase precipitation * crack formation * TiAl intermetallic compound
Subject RIV: JG - Metallurgy

Heat treatments were conducted under several conditions in order to clarify the effect of holding temperature, time and cooling rate on microstructure of Ti-46Al-7Nb-0.7Cr-0.2Ni-0.1Si and Ti-45Al-10V (mol%) alloys. Indentation tests were performed in order to understand the effect of beta phase precipitation on crack formation of microstructure controlled Ti-45Al-10V alloy. As for Ti-46Al-7Nb-0.7Cr-0.2Ni-0.1Si alloy, phase condition on several temperatures was estimated experimentally. It is found that the cooling rate where the massive transformation occurs ranges from -300K/s to -5K/s. Furthermore, in order to obtain the fully lamellar structure, the alloy should be cooled slower than -1K/s. As regards the heat treatment on Ti-45Al-10V alloy, fully lamellar structure was formed by cooling from (alfa+gama) two phase state. However, beta precipitates were observed near the lamellar colony boundaries when the material was cooled from (beta+gama) two phase state. Though the cracks are not observed at the specimen cooled at -8x10-2K/s from (alfa+gama) two phase state, the cracks induced by Vickers indentation are observed in most of the heat treated specimens.
Permanent Link: http://hdl.handle.net/11104/0211308